Two commonly used motor vehicles for transporting loads on roadways are tractor trailers and tank trucks or “tankers”. Tractor trailers typically comprise a towing vehicle, commonly referred to as the tractor or the truck, and one or more semi-trailers for carrying cargo. The semi-trailer is attached to the tractor at a point just forward of the rear-most axle of the tractor such that a fraction of the weight of the trailer is carried by the tractor.
Tankers are primarily used to carry various liquid or semi-liquid cargoes. A tanker typically comprises a sealed cylindrical tank lying horizontally on a truck bed and often includes an integral pumping system for pumping material in and out of the tank. Large tankers can have a capacity ranging from 21,000 to 44,000 L (5,500 to 11,600 US gallons), while small tankers have a capacity less than 11,000 L (3,000 US gallons). Tankers may include additional features such as insulation, pressurization, and/or compartmentalization, depending on the cargoes being carried. Due to the cylindrical shape, a tanker has a high center of gravity which makes them more difficult to drive than a tractor trailer.
For transporting various fluid materials, including mixtures of liquids and solids like a sludge or slurry, both tractor trailers and tankers can be used. A vacuum tanker is a specific type of tanker that is typically used for transporting sludge and slurries such as drilling muds, drill cuttings and cement from oil and gas well sites, as well as sewage and waste from cleaning streets, sewers, septic tanks and grease bins. A vacuum tanker uses a heavy duty vacuum system for pneumatically loading and unloading material into and out of the tank through suction lines. While vacuum tankers can be effective for transporting slurries/sludge, they are generally more expensive than tractor trailers and the inside of the tank can be difficult to access for cleaning and maintenance purposes. As such, dump truck tractor trailers having a container on the trailer are often used for transporting a sludge/slurry.
Using a dump truck tractor trailer allows a sludge/slurry in the container to be quickly and easily unloaded, as one side or end of the container can lift up and a gate opens on the opposite side or end to allow the sludge/slurry to flow out of the container through the gate. Using an open top container dump truck allows a sludge/slurry to easily be loaded into the container using an auger and allows easy access to the container for cleaning and maintenance purposes. However, the sludge/slurry can slosh around in the container and spill over the sides of the container during transport. Using a closed container can help keep the sludge/slurry in the container, however it makes it more difficult to load and clean the container. Furthermore, the sludge/slurry can still slosh around in the container during transport, making it difficult for the driver to handle the truck under various driving conditions. The slurry/sludge may also accumulate at one end of the truck when the driver accelerates or decelerates, or when the truck is driving up or down a hill. This is especially problematic driving uphill, as the slurry/sludge may amass at the rear end of the container, moving the center of load to the rear of the trailer and removing the load from the truck drive axles that are located near the front of the trailer, causing the truck to be unable to drive up the hill. This is especially problematic at oil and gas sites where steep hills and rough roads are often encountered.
To solve the problem of a slurry/sludge sloshing around and/or accumulating at one end of the container, the slurry/sludge may be mixed with another material for stabilization. At oil and gas sites, sawdust is often mixed with a slurry of drill cuttings to stabilize the drill cuttings for transport. However this results in increased costs and time due to additional steps, additional materials, additional labor, and an increased volume of material to transport. Furthermore, if the slurry is to be transported to a site for separation and recovery of the slurry components the addition of a further component complicates the separation process and creates further waste material.
Tankers and containers may be insulated to help prevent the contents from freezing in cold temperatures, which makes it difficult to unload the contents from the tank/container. A drawback with insulation is that it adds extra bulk and weight to the tank/container, which can reduce the volume and weight of material that can be transported in a load. While the insulation may be useful when temperatures are near or below freezing, tanks/containers are often used in locations with seasonal variation, and the insulation adds unnecessary weight/bulk during the warmer months
Accordingly, there is a need for an economical transport trailer having a container for transporting a sludge/slurry that is easy to unload and unload, and wherein the sludge/slurry is stabilized in the container without adding further materials to the sludge/slurry. There is also a need for a transport trailer container that can be cleaned easily and that prevents the contents from freezing in cold temperatures
A review of the prior art reveals several patents related to various style transport trucks and tankers.
U.S. Pat. No. 4,389,314 to Petretti teaches a flush tank end-dump style eductor truck adapted to siphon debris from a sewer/catch basin. The truck includes a settling tank having a series of vertical hinged internal baffles dividing the tank into sections and a hinged rear door. When a mixture of debris and liquid is siphoned into the rear-most section of the settling tank, the heavier debris falls to the floor and the fluid is distributed through all the settling tank sections by flowing through large openings in the internal baffles. The baffle near the front end of the tank includes small openings to strain out the fine debris from the fluid as it flows into the front-end compartment. This strained fluid can then by re-used to further flush out the sewer/catch basin. When the settling tank is to be emptied, the tank is pivoted upwardly by a hydraulic cylinder and the rear door and internal baffles swing open around upper pivots to permit debris to be cleaned out. The rear door contains a hydraulically-activated latch mechanism to prevent the door from opening until the tank is in a full upward tilt position.
U.S. Pat. No. 4,136,973 to van der Lely teaches a cylindrical transport tank for transporting a mixture of manure and water having guide members to produce recirculating and swirling motions of the mixture within the tank as the result of normal movements of the tank during transportation. A first guide member is inclined upwardly from the rear of the tank to the front of the tank, curving downwards at the front, to cause the mixture to surge forward up the guide member during stopping motions. A second guide member extends from the top of the tank downwardly at an inclination opposite the first guide member to prevent the mixture from sloshing backwards to the rear of the tank after it has surged forward. The rearmost portion of the first guide member is hinged, thereby allowing the returning mixture to rotate this portion of the first guide upwardly and flow toward a rear discharge valve.
U.S. Pat. No. 6,547,091 to Hagenbuch teaches a water tanker having internal baffles for preventing surging of the water during transportation. The internal baffles are configured to allow maintenance access between compartments defined by the baffles Specifically, there are lateral baffle doors along the interior sides of the tanker that open and close like a door from a lateral direction to a longitudinal direction, such that when all the doors are in an open longitudinal direction, workers have unobstructed access to the side sections of the tanker from the front end to the rear end.
U.S. Pat. No. 4,775,070 to Williams teaches an internal baffle system for a tank to prevent fluid surges. Specifically, the interior of the tank is divided into upper and lower compartments by a plurality of upper stationary vertical baffles extending downward from the top interior wall of the tank to a middle point within the tank, and a plurality of lower stationary vertical baffles extending upward from the bottom interior floor of the tank to the middle point. A rotatable member is positioned in the middle of the tank between the upper and lower baffles and is moveable between an open and closed position to either allow or block fluid from flowing between the upper and lower compartment.
U.S. Pat. No. 4,251,005 to Sons et al teaches a tank for transporting liquids having a baffle system to control liquid surges. The baffle system includes large longitudinal cylindrical hollow baffles extending the length of the tank and transverse support partitions extending between the side walls of the tank.
U.S. Pat. No. 2,552,119 to Scharenberg teaches a collapsible fuel tank for an aircraft having “cross elements” or baffles positioned transversely in the interior of the tank and spaced apart longitudinally from the front to the rear of the tank to provide internal support. The baffles are generally circular in shape and have a vertically positioned hinge in the middle of the baffle to allow the baffle to fold in half when the fuel tank is collapsed.
U.S. Pat. No. 3,905,308 to Laudato, Jr. teaches a railway car having a built-in swimming pool containing moveable vertical hinged, baffles that operate automatically to contain the water when the train accelerates, decelerates or stops. The baffles are hinged to a side wall of the train, and lie relatively flat against the wall in the retracted position. The baffles are actuated automatically when the braking system of the train is applied, swinging outwardly from the side wall to extend transversely towards the opposite side wall, extending across the pool to inhibit forward or rearward displacement of the water.
U.S. Pat. No. 4,331,342 to van der Lely teaches a tank wagon for liquid material having internal partitions with dampeners that divide the tank into compartments and counteract movement of the liquid material with respect to the tank in one direction only: from the rear to the front of the tank. The internal vertical partitions extend between the side walls of the tank, leaving an opening between the bottom edge of the partition and the tank floor. The bottom section of the partition has a flap that rests in an open position and allows fluid movement at the bottom of the tank when the tank is at a constant speed or accelerating. When the tank decelerates and fluid is thrust towards the front of the tank, the fluid pushes the flap into a closed position to limit fluid movement towards the front of the tank.